1. Histrionicotoxin and its congeners has become such an important probe for the study of ion (potassium) movement in (nicotinic) acetylcholine receptors that the demand for this compound exceed supply. In order to close this gap a substitute was sought and found in the form of phencyclidine and analogs obtained by functionalization of photochemically formed cage compounds. 2. A novel powerful cholinergic agonist has been discovered in the toxic principle of the cyanophyte Anabaene flos-aquae, viz., the rigid bicyclic homologous tropane aminoketone anatoxin-a. This alkaloid has now been characterized as the most useful agonist and substitute for acetylcholine on nicotric receptors. 3. A synthesis of the toxin of the lady but, adaline has been worked out by intramolecular 1,3-dipolar addition of a suitably substitued piperidine nitrone. 4. In collarobation with the Section on Medicinal Chemistry (Dr. Brossi, Takahashi) simplified analogs of histrionicotoxin have been synthesized for extensive electrophysiological and pharmacological evaluation.